Eating fruits and vegetables is second nature to humans, however, the ability to extract sufficient nutrients from plant material is a special adaptation. Once such an evolutionary hurdle is overcome, it may allow a lineage access to previously unexploited resources and thus lead the way to increased species richness, as shown in studies of insects, mammals and dinosaurs.

A new study published in PNAS examines the role of herbivory–eating plants–on the diversification of crustaceans, a diverse and important group of arthropods dominating aquatic environments. The authors carry out a phylogenetic analysis of the distribution of the trait followed by an examination of shifts in species richness within each lineage.

The authors identify 31 independent lineages of plant-feeding crustaceans and find that these have 21 times more species than their nearest predatory or scavenging relatives. Using GBIF-mediated occurrences of all species, the authors showed that these findings were not likely confounded by distributional patterns, suggesting that the difficult evolutionary path of shifting diets to plants indeed promotes speciation among herbivorous crustaceans.

Poore AGB, Ahyong ST, Lowry JK and Sotka EE (2017) Plant feeding promotes diversification in the Crustacea. Proceedings of the National Academy of Sciences. Proceedings of the National Academy of Sciences 114(33): 8829–8834. Available at: https://doi.org/10.1073/pnas.1706399114.